DOZENS of convicted sex offenders have gone missing, police have revealed.

Greater Manchester Police said 25 registered sex offenders were missing, including one who disappeared in September 2005 and three others who went missing in 2006.

It is not clear how many, if any, are from Bolton.

The missing criminals are among nearly 400 sex offenders who have evaded monitoring across the UK.

New figures show 396 registered sex offenders are wanted because their whereabouts are unknown, including some who have been missing for more than a decade.

One convicted sex offender in Gloucestershire has been missing since the year 2000, while another in Northumbria disappeared in May 2002.

Humberside Police said the whereabouts of one registered sex offender had been unknown since September 2004.

Registered sex offenders - including rapists and paedophiles - are required to inform police and probation officers of their addresses and are supposed to be monitored by officials working under multi-agency public protection arrangements (MAPPA).

But figures released under the Freedom of Information Act show that 39 forces had missing registered sex offenders in their areas in February or early March.

They stressed the figures could change as arrests are made or new cases come to light.

Every force to respond to the request refused to name those missing over concerns of vigilante attacks or because the information was exempt under data protection laws.

The Metropolitan Police, the UK's largest force, said 167 registered sex offenders were wanted in London alone, including one who had been missing for 14 years.

West Midlands Police said 39 registered sex offenders were missing, including one since 2006 and nine between 2010 and 2012.

Essex and Sussex Police each said 11 registered sex offenders were missing in their force areas, while Cambridgeshire Police said 10 registered sex offenders were wanted because their whereabouts were unknown.

The Police Service of Northern Ireland (PSNI) said three sex offenders were "currently wanted" but did not reveal when the offenders went missing.

Police Scotland said none of the 4,775 registered sex offenders in the country was missing as of February 16.

The NSPCC described the figures as "alarming" and said its own research had found there was just one police staff member responsible for every 50 registered sex offenders.

Jon Brown, the charity's lead for tackling sexual abuse, said: "About half of those on the register are offenders who have raped or sexually assaulted children, or committed online child abuse image offences, however most just receive one police visit a year after they have been released from prison and a period of supervision.

"The monitoring of registered sex offenders in communities needs urgent attention by the government to ensure it is fit for purpose."

A Home Office spokesman said: "The UK has some of the toughest powers in the world to deal with sex offenders and we are committed to ensuring the system is as robust as possible.

"It is for the police to manage offenders in their area, but we work closely with forces to ensure legislation is effective and that officers have all the tools they need."